The micro-organisms of fermentation practically considered / by Alfred Jörgensen.

  • Jörgensen, Alfred, 1848-1925.
Date:
1889
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Licence: Public Domain Mark

Credit: The micro-organisms of fermentation practically considered / by Alfred Jörgensen. Source: Wellcome Collection.

    127/198 (page 105)
    of revievv, tlie so-called Sacch. ainculaUi^s and Pasteur’s Torula forms. From Hansen’s investigations of tlie behaviour of the Saccharomyces towards the different kinds of sugar, it appears that large specific difierences in this respect obtain among the species. The six species treated of on pages 109—-124 all secrete invertase ; they convert Saccharose into invert sugar and then ferment the latter; they ferment dextrose and maitose, but not lactose. The same remarks apply to all the industrial bottom-yeasts which have been at present examined, and, indeed, to all the alcoholic ferments examined by the author. Sacch. Marxianus produces no fermentation in maltose and lactose ; it inverts Saccharose and excites fermentation in Solutions of this sugar ; dextrose dissolved in yeast-water is also fermented by this ferment. Sacch. exigiius behaves towards the sugars exactly as the last-mentioned ferment. Sacch. onembranoefaciens does not cause an alcoholic fermentation either in beer^wort, or in Solutions of Saccharose, dextrose, maltose, or lactose ; neither is it able to invert Saccharose. Among the ferments resembling the Saccharomyces Mycoderma cerevisioi can bring about no alcoholic fermenta- tion in the four sugars mentioned above, and it is also not capable of inverting Saccharose. Sacch. apiculahts produces a slight alcoholic fermentation in beer-wort; it does not ferment maltose, and can neither invert nor ferment Saccharose. Hansen formerly assigned three of the Torula forms to the alcoholic ferments, and two of these secreted invertase. Since then he has examined some new species of which the first does not ferment maltose, but inverts Saccharose, and excites a vigorous fermentation in Saccharose—and dextrose— nutritive Solutions. The second gives 1 per cent. by volume of alcohol in beer-wort; it does not ferment maltose and Saccharose, neither does it invert the latter; it ferments dextrose Solutions. Monilia candida ferments beer-wort and dextrose ; in pure maltose Solutions it neither gi’ows nor excites fermentation.